Fragmentation weapon



Nov. 10, 1964 ZERNOW ETAL 3,156,188

FRAGMENTATION WEAPON Filed March 1, 1962 INVENTOR. LOUIS ZERNOW KENNETHN. REYENHAGEN ATTORNEY Fla-10 W United States Patent 0 3,155,188FIhQGMENTATiGlQ WEAFGN Louis Zernow, Glendora, and Kenneth N.Kreyenhagen,

West Io-visa, Qalifl, assignors to Aeroiet-General- (Jorporation, Aznsa,@alih, a corporation of Ghio Mar. l, 1962, Ser. No. 177,699 in Qlahns.(El. NZ-57) This invention relates to a fragmentation device, and moreparticularly to a fragmentation device provided with means forcontrolling the size and shape of the fragments produced.

Fragmentation devices are primarily useful for military purposes,although there may also be a use for them in certain industrialapplications. With respect to military requirements, uncontrolledfragmentation in a fragmentation-type weapon is undesirable because theexplosion of the weapon results in the production of fragments whichhave a variation in size and weight. This variation in fragment sizereduces the efficiency of the weapon against targets for which it wasdesigned because a large proportion of the fragments will either be toolarge, thus wastefully overlcilling the target, or will be ineifectuallysmall. It is apparent, therefore, that if the size of the fragments iscontrolled, the lethality of the weapon would be increased.Consequently, the size and weight of the weapon could be reduced withoutdecreasing its effectiveness.

Heretofore, fragment size in fragmentation type Weapons has generallybeen controlled by precutting grooves in the weapon or casing duringproduction to establish preferential fracture lines in the casing. Thesecutting or grooving operations, however, are expensive and timeconsuming, and they furthermore weaken the casing so that the usefulnessof such weapons for launching from a gun, for example, is limited. Whatis needed, therefore, and comprises an important object of thisinvention is to provide a simple and economical method and apparatus forprecisely controlling the size of fragments in a fragmentation typeweapon which does not involve weak? ening, precutting, or grooving thecasing.

The invention in its broadest aspect comprises filling a metal casingwith high explosive material. An inert barrier provided withperforations or openings surrounds, encases or is contiguous with thehigh explosive material in spaced relation to the casing. When the ighexplosive material is detonated, the resulting detonation wave isinterrupted by the barrier, but continuous unhindered through theperforations or openings, forming a network of intersecting shock wavesbeyond the barrier. Reinforcement of these shock waves occurs alongplanes of interaction, causing preferential fractures by cutting orgrooving in the casings where these planes reach the casing. If theperforations or openings in the barrier are equally spaced from eachother, the size of the casing fragments will also be generally equal. Byvarying the spacing of the perforations in the barrier, the size of thecasing fragments will vary. In this way, the size of one group offragments can be controlled for optimum effectiveness against personneland the size of another group can be controlled for optimum eiectivenessagainst equipment.

This and other objects of this invention will become more apparent whenread in the light of the accompanying drawings and specificationwherein:

FIGURE 1a is a sectional view illustrating the application of theinvention to a spherical fragmentation weapon;

FIGURE lb is a plan View of a spherical weapon shown in FlGURE la;

FIGURE 2 discloses a portion of a cylindrical pen forated barrier havinground perforations;

FIGURE 3 discloses a modified perforated barrier with squareperforations;

FIGURE 4 discloses a semi-spherical perforated barrier with roundperforations;

FIGURE 5 discloses a barrier formed from a wire screen;

FIGURE 6:: discloses a longitudinal sectional view showing thisinvention employed in a cylindrical fragmentation weapon;

FIGURE 6!; is a plan view of the weapon shown in FIGURE 6a;

FIGURE 7 discloses the shape of one typical fragment which can beobtained by controlling the pattern of perforations in the barrier;

FIGURE 8 is a longitudinal sectional view of a cylindrical weapon with amodified perforate barrier;

FIGURE 9 discloses a development of a. portion of a modified perforatebarrier shown in FIGURE 8 but showing in greater detail the two groupsof perforations where the perforations in one group are spaced furtherapart than the perforations in the other group; and

FIGURE 10 is a side sectional view of an enlarged portion of thecylindrical weapon shown in FIGURE 8, and showing in particular, theinteraction of the shock waves passing through the perforate barrier.

Referring now to FIGURE 1 of the drawing, one embodiment of theinvention comprises a spherical fragmentation-type weaponindicated-generally by the reference numeral iii. It is understood,however, that the shape of weapon is not critical. The weapon showncomprises an outer spherical casin 12; preferably formed from metal. Theinterior of the casing is filled with a high explosive mater alindicated generally by the reference numeral 14. A concentric,spherical, inert, perforated barrier 16 is embedded in the highexplosive material.

The perforations 19 in the barrier in the embodiment shown in FTGURE 1are filled with explosives and are substantially equally spaced fromeach other for reasons to become apparent below. In addition, thebarrier is in spaced relation to the inner surface of casing 12. Thehigh explosive charge is detonated by means of a conventional suitableigniter it; which initiates the explosion, preferably by acting on adetonating element 13' at the center of the spherical casing.

When the igniter is actuated and detonates the high explosive material,the detonation wave propagates radially outward as an advancingspherical front. When this wave front reaches the inert barrier itsfurther propagation is interrupted except at the perforations.

Those parts of the wave which pass through the perforations act as pointsources to form a network of tiny spherical detonation wavelets 20,shown in dotted lines in FIGURE 1. these detonation wavelets arecentered around each of the perforations. 3

As these detonation wavelets propagate outwardly, they interact witheach other and reinforce each other along planes of interactionindicated by dotted lines 2d, shown in FIGURE 1. Since the perforationsin the perforated wave barrier to are generally equally spaced from eachother, their planes of interaction will also be uniformly spaced fromeach other. Consequently, the casing will break into fragments which aresubstantially equal in size. Therefore the size of the fragments dependsprimarily on the spacing of the perforations in the wave barrier.

, It has been found that in the above-described structure the size ofthe fragments and their uniformity is af- In the region beyond thebarrier,

' tween the barrier 16 and the outer casing 12.

I al

wave reinforcement along the planes of interaction will be maximizedcausing the casing to break into well defined fragments.

In addition, it has been found that the effectiveness of the device isalso sensitive to the shape of the detonation wave reaching theperforated barrier to, and it is desirable, though not mandatory, forall parts of the detonation wave toreach the barrier at about the sameinstant. For this reason, point initiationof the high explosive materialat the center of the spherical casing is desirable. detonation of thehigh explosive material will produce casing fragments of uniform sizeand each of the fragments will have imparted to it substantially thesame amount of energy. This will result in a more efficient, betterperforming weapon.

The principles of this invention have been aiso applied to a cylindricalfragmentation-type weapon shown in FIGURES 6a and 6b and indicatedgenerally by the reference numeral 26. This Weapon is provided with anouter cylindrical casing 28 and is filled with a suitable high explosivematerial 30. An inert perforated barrier 32 is contiguous with the highexplosive material in spaced relation to the outer casing 28. As seen,the perforated barrier is cylindrical and is parallel to the outercasing 28. In this embodiment the igniter element 34 includes anactuating element 36 outside the casing and conventional means includingdetonating elements 38 along the axis 29 of the casing for detonatingthe explosive material from at least one point in the axis of thecylindrical casing. The spacing between the perforated barrier and theouter casing, the thickness of the perforated wave barrier, and thespacing between the perforations in the wave barrier, are as describedabove in connection with the embodiment shown in FIGURE 1.

It is apparent that the shape and size of the fragments produced whenthe high explosive material is detonated depends primarily on thespacing of the perforations. As shown in FIGURES 2, 3, and 4, goodresults can be obtained using a perforated barrier with round or squareperforations extending therethrough. Barriers having perforations withother shapes may also be satisfactory. If the rows of perforations arestaggered from each other, as shown in FIGURES 2, 3, and 4, the outercasing 12 or 28 will shatter into generally hexagonally shaped fragments40 as shown in FIGURE 7. If the rows are paral-- l'el columns,square-shaped fragments will result. Intermediate shapes can also beobtained using other perforate patterns.

As shownin FIGURE 5, it is, also possible for the barrier to be formedfrom a wire screen 42. One advantage of the use of the wire screeninstead of a perforated barrier formed from metal or plastic is that thescreen may be more economical to fabricate than the barrier incomparison to the perforated barrier disclosed in FIGURES 2, 3, and 4. i

In some circumstances, it is desirable for a fragmentation weapon to beeffective against personnel and equipment. 1 Since, in general, largercasing fragments are required for effective use against equipment thanagainst personnel, it would be desirable to design the casing. so itshatters into two or more controlled groups of fragments, where the sizeof one group of fragments is optimized for use against personnel, andthe size of the other group of fragments would be optimized for useagainst equipment.

As described above, the spacing of the perforations in the wave barrierprimarily determines the size of the fragments. Consequently, if it isdesired to cause the With the arrangement described above, the.

casing to shatter into two or more groups of fragments having adifferent size, the perforated barrier must have a corresponding numberof portions wherein the spacing between the perforations in one portionis different from the spacing of the perforations .in another portion.

The modified cylindrical fragmentation device 40 shown in FIGURE 8illustrates this possibility. As shown,

it includes an outer cylindrical case 42 and an innerperforated barrier44 surrounding the explosive. As seen.

in FIGURES 8 and 9, the perforated barrier in this par ticularembodiment has two groups of perforations 46 and 4-8 and the spacings ofthe perforations in each group are different. It is further noted, asseen in FIGURES 8 and 10, that the portions of the wave barriercontaining perforations 46 are closer to the casing 4-2 than theportions containing perforations 48. This is in accordance with theoptimum conditions recited above wherein the thickness of the wavebarrier 44 is designed so that it is equal to the spacing of the wavebarrier 44 from the cats ing 42, and so that the spacing between theperforations.

is designed to be twice the thickness of the wave barrier or the spacingbetween the Wave barrier and the casing.

In particular, if the portion of the perforated barrier 44 containingperforations 46'has a thickness I2 then the spacing between this portionof the perforated barrier and the casing 42 is preferably set equal to hand the spacing between perforations 46 is preferably'set equal to 211(see FIGURE 10). Similarly, if the perforations 48 are spaced from eachother at a distance 2/1 then the portion of the barrier containingperforations 48 should preferably have a thickness k and be separatedfrom the barrier by a distance I1 (see FIGURE 10).

With this arrangement, as seen in FIGURE 10, when the high explosivematerial 50 in the casing 42 is detonated by actuating element andigniter 4% acting on detonating element 51, the detonation wavepropagates outwardly. When this detonation wave reaches the perforatedbarrier, the portions of the wave which pass through the perforatedbarrier'act as point sources to produce a network of tiny sphericaldetonation wavelets 52 and 54 centered around perforations 4-6 and 43respectively.

As these detonation wavelets propagate outwardly, they intersect eachother and reinforce each other along planes of interaction 56 and 58respectively. Consequently, the casing will shatter into two groups offragments, wherein the fragments in one group are larger than thefragments in the other.

It is further apparent that the principles applied above can be extendedto cause the casing to shatter into addi tional groups of fragmentswherein the fragments in each group are substantially the same size.rated barrier 44 will shatter when the device is detonated, the wavebarrier itself could be formed from metal or some other suitablematerial to increase the number of fragments produced and thus increasethe effectiveness of the weapon.

It is to be understood that the form of the invention herewith shown anddescribed is to be taken as a preferred example of the same, and thatvarious changes in V and the resulting detonation wave coacting withsaid barrier so that when the detonation Wave reaches said barrier,parts of the detonation wave pass through the openings and form anetwork of detonation wave interactions Since the perfobeyond thebarrier in the space between the barrier and the casing which producepreferential fractures in the casing along the planes of the detonationwave interactions.

2. The apparatus described in claim 1 wherein said outer casing isspherical in shape and said barrier is spherical and concentric withsaid casing.

3. The apparatus set forth in claim 2 wherein said barrier is formedfrom wire mesh.

4. The apparatus set forth in claim 2 wherein said means for detonatingthe explosive material is disposed at a point in the center of thespherical casing.

5. The apparatus described in claim 1 wherein said outer casing iscylindrical and said barrier is cylindrical and concentric with saidouter casing.

6. The apparatus set forth in claim 5 wherein said means for detonatingthe explosive material is disposed on at least one point on the axis ofsaid cylindrical casing.

7. An apparatus of the class described comprising an outer casing,explosive material in said casing, a wave barrier having generallyequally spaced openings and surrounding said explosive material, saidwave barrier being in spaced parallel relation to said casing and at adistance therefrom which is substantially equal to the thickness of saidbarrier, the spacing between said generally equally spaced openingsbeing substantially equal to twice the thickness of said Wave barrier,and means for detonating said explosive material whereby when theresulting detonation wave reaches the wave barrier, parts of the wavepass unhindered through the openings and form a network of equallyspaced detonation wave interactions beyond the barrier which producepreferential fractures in the casing along the planes of the waveinteractions, thereby producing casing fragments which are substantiallyequal in size.

8. The apparatus described in claim 7 wherein said outer casing is asurface of revolution and said barrier is equidistant from said casing,and said means for detonating the explosive material being disposed insaid casing.

9. An apparatus of the class described comprising an outer casing,expolsive material in said casing, a wave barrier having a plurality ofgroups of perforations extending therethrough, the spacing between theperforations in any one group different from the spacing between theperforations in any other group, said wave barrier being disposed aboutsaid explosive material and in spaced parallel relation to said casing,the thickness of the portion of the perforated barrier containing anyone group of perforations equal to one-half the spacing between theperforations in that group and equal to the spacing between that portionof the perforated barrier and the outer casing, and means for detonatingsaid explosive material whereby when the resulting detonation wavereaches the perforated barrier, parts of the wave pass through theperforations and serve as point sources for a network of expandingdetonation waves centered around each perforation, said expanding wavesinteracting with each other so that the waves centered about theperforations in each group reinforce each other along planes ofinteraction, thereby producing fragments having a size determined by thespacing between the perforations in the group, whereby each group ofperforations produce waves which interact with each other to shatter thecasing into groups of fragments wherein the size of the fragments ineach group is related to the spacing between the perforations in anassociated portion of the perforated barrier.

10. An apparatus of the class described comprising an outer casing,explosive material in said casing, a wave barrier having a plurality ofgroups of openings extending therethrough, the spacing between theopenings in any one group different from the spacing between theopenings in any other group, said wave barrier encasing said explosivematerial and in spaced parallel relation to said casing, and means fordetonating said explosive material whereby when the resulting detonationwave reaches the barrier, parts of the wave pass through the openingsand serve as a point sources for a network of expanding detonation wavescentered around each opening, said expanding waves interacting with eachother so that the waves centered around the openings in each groupreinforce each other along planes of interaction, thereby fracturing theeasing into fragments having a size determined by the spacing betweenthe openings in the associated group.

References Cited in the file of this patent UNITED STATES PATENTS 32,702McIntyre July 2, 1861 1,015,944 Du Pont Jan. 30, 1912 1,211,001Steinmetz Jan. 2, 1917 2,413,008 Taglialatela Dec. 24, 1946 FOREIGNPATENTS 284,108 Germany May 10, 1915

1. AN APPARATUS OF THE CLASS DESCRIBED COMPRISING AN OUTER UNITARYCASING OF INTEGRAL NON-SCORED CONSTRUCTION, EXPLOSIVE MATERIAL IN THECASING, A BARRIER PROVIDED WITH OPENINGS DISPOSED ABOUT SAID EXPLOSIVEMATERIAL AND COMPLETELY ENCASING SAID EXPLOSIVE MATERIAL, SAID BARRIERBEING DISPOSED IN INWARDLY SPACED RELATION TO SAID CASING TO DEFINE ASUBSTANTIALLY CONTINUOUS UNOBSTRUCTED SPACE THEREBETWEEN, MEANS FORDETONATING SAID EXPLOSIVE MATERIAL, AND THE RESULTING DETONATION WAVECOACTING WITH SAID BARRIER SO THAT WHEN THE DETONATION WAVE REACHES SAIDBAR-